Vibratory Spiral Conveyor

ABSTRACT

A spiral cooler and a process for cooling workpieces are proposed. A very simple structure is enabled by the workpieces being cooled in counterflow by cooling air, preferably a negative pressure being produced in the conveyor channel by branching off and redelivering a partial flow.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a spiral cooler for cooling of workpieces, especially castings, by cooling air, with a preferably coiled or spiral conveyor channel for the workpieces and with an inlet air means and exit air means for cooling air.

2. Description of Related Art

Published International Patent Application WO 2004/058602 discloses a spiral cooler with a coiled conveyor channel for workpieces to be cooled by cooling air. The cooling air is supplied by inlet air channels which extend radially into the conveyor channel so that the workpieces located in the conveyor channel are exposed to cooling air in the axial direction. Exhaust takes place in the radial direction via the corresponding exhaust channels which extend axially within the spiral cooler. This structure is very complex. Moreover, the inlet air channel can be very easily damaged by workpieces in the conveyor channel.

German Patent DE 41 06 712 C2 discloses a spiral conveyor in which gas such as cooling air is supplied to a conveyor channel for the workpieces by mean of radially extending tubular feed lines which are connected to a central stay pipe so that the gas is incident on the workpieces essentially in the axial direction. The gas is discharged again via the open coil end. This structure is also complex.

German Patent DE 42 28 543 C1 discloses a spiral conveyor in which gas for heat exchange is repeatedly supplied and discharged. This structure is also complex.

SUMMARY OF THE INVENTION

The object of this invention is to devise a spiral cooler and a process for cooling of workpieces, a simple, durable structure of the spiral cooler being enabled with good cooling action.

One important idea of this invention is to cool the workpieces in counterflow by cooling air, the cooling air being to the conveyor channel preferably solely in the area of the second end at which the cooled workpieces are delivered and the exhaust air being removed preferably exclusively in the area of the first end at which the workpieces to be cooled are delivered into the conveyor channel. This allows a very simple and thus economical and also durable structure. In particular, no axial or radial air channels, collecting boxes or the like are necessary. Rather an at least essentially continuous inside and outside wall of the conveyor channel can be implemented.

According to another preferred aspect, negative pressure is produced in the conveyor channel at least over a significant region of the conveyor channel. This prevents unwanted emergence of dust and enables, for example, also opening of check openings during operation.

The negative pressure is easily and efficiently produced—even for a high flow resistance for the cooling air in the conveyor channel—in that a partial flow of cooling air is exhausted from the conveyor channel and delivered again into the conveyor channel with a higher speed. This takes place especially in the vicinity of the first end, therefore in the vicinity of the delivery of the workpieces to be cooled or the exit air means. Thus, depending on the portion of the partial flow in the total flow and/or the speed with which the partial flow is delivered again into the conveyor channel, a negative pressure can be produced up to the second end—output end—of the conveyor channel. Furthermore, by varying the proportion or speed of the component flow the negative pressure or optionally the flow of ambient air drawn into the conveyor channel can be controlled.

Other advantages, features, properties and aspects of this invention will become apparent from the following description in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a spiral cooler as claimed in the invention; and

FIG. 2 shows a schematic cross section of the spiral cooler.

DETAILED DESCRIPTION OF INVENTION

In the figures, the same reference numbers are used for the same or similar parts, the corresponding properties and advantages being achieved even if a repeated description is omitted for reasons of simplification.

FIGS. 1 & 2 schematically show a spiral cooler 1 in accordance with the invention in one preferred embodiment. The spiral cooler 1 is used to cool workpieces 2, especially castings, such as brake disks or the like, as indicated in FIG. 1.

The cooling takes place with cooling air. However, if necessary, also another gas can be used for cooling. Alternatively or in addition, additional media can be used for cooling.

The spiral cooler 1 has a preferably at least an essentially coiled or spiral conveyor channel 3 for the workpieces 2. The conveyor channel 3 preferably represents a conveyor for the workpieces that is closed on all sides. In FIGS. 1 & 2, the upper coil turn of the conveyor channel 3 is shown open—therefore not hidden—on the left side solely for purposes of illustration.

In the illustrated example, the length of the conveyor channel 3, therefore the conveying distance for the workpieces 2 in the spiral cooler 1, is preferably more than 50 m. The conveyor channel 3 in the illustrated embodiment has five coil turns located on top of one another.

The spiral cooler 1 has an inlet air means 4 for supply of cooling air and an exit air means 5 for discharge of cooling air, as shown in FIG. 1. The arrow Z indicates the feed direction of the cooling air. The arrow A indicates the direction of the removed exit air.

The workpieces 2 are delivered into the conveyor channel 3 at the first end 6 and are discharged cooled on the other, second end 7 of the conveyor channel 3. To cool the workpieces 2 in counterflow, the inlet air means 4 in the area of the second end 7 is connected to the conveyor channel 3 and the exit air means 5 is connected to the conveyor channel 3 in the area of the first end 6. In particular, only one end-side feed and discharge of cooling air takes place, so that the inlet air and exit air channels conventional in the prior art for axial or radial feed and discharge of cooling air are unnecessary.

The cooling air is supplied in the area of the second end 7 preferably from obliquely overhead into the conveyor channel, especially by means of a nozzle or the like (not shown).

The spiral cooler 1 is preferably made such that ambient air together with the cooling air is delivered into the second end 7, especially is taken in by injector action. The proportion of ambient air in the total flow in the conveyor channel is preferably 10% to 70%, especially essentially 50% or more. This allows, for example, a reduction of the dust burden in the vicinity of the spiral cooler 1.

Preferably, negative pressure is produced in the conveyor channel 3, at least over a considerable area. Preferably, a partial flow of cooling air is exhausted from the conveyor channel 3 and delivered again into the conveyor channel 3 with higher speed. In the illustrated example, the spiral cooler 1 has a connection 8 for exhaust to which a fan 9 is connected which then delivers the partial flow again with higher speed to the conveyor channel 3, preferably at least essentially tangentially and/or horizontally, especially by means of a nozzle 10 or the like.

The branching or exhaust of the partial flow and redelivery of the partial flow take place preferably in the vicinity of the first end 6 of the conveyor channel 3, especially roughly one coil turn in front of the first end 6. The distance of the nozzle 10 from the branch through the connection 8 along the conveyor channel 3 is preferably roughly ¼ of a coil turn.

As a result of the exhaust of the partial flow and redelivery into the conveyor channel 3, the desired negative pressure in the conveyor channel 3 can be produced before branching or exhausting. In particular, the negative pressure in the conveyor channel is produced up to the second end 7 or up to the connection of the inlet air means 4 in this way. The negative pressure in the area in front of the connection 8—with respect to the flow direction of the cooling air therefore upstream—is preferably at least 2000 Pa, especially 2500 Pa or more.

The partial flow is preferably at least 50%, especially roughly 70 to 90% of the entire cooling air flow in the conveyor channel 3. The higher speed with which the partial flow is delivered again into the conveyor channel 3 is greater at least by a factor of 2, preferably 3 or more, than the speed of the cooling air in the conveyor channel 3 in front of the connection 8.

After delivery of the partial flow, an overpressure of roughly 500 Pa to 800 Pa can be set in the conveyor channel 3. In route to the first end 6, this pressure then drops to a negative pressure of roughly 200 Pa as a result of the corresponding exhaust through the exit air means 5.

It is noted that the values for the negative pressure are given as positive values. A higher negative pressure therefore leads to a higher value. As a relative value compared to normal pressure or ambient pressure these values can then be regarded as negative relative values relative to normal pressure.

The flow velocity of the cooling air in the conveyor channel 3 is, on average preferably, at least 10 m/s, especially roughly 15 m/s or more. Thus, a very turbulent or relatively turbulent flow around the workpieces 2 with correspondingly good cooling action can be achieved.

With respect to the cooling air flow rate (mass flow), it is noted that it is kept preferably at least essentially constant. The flow speed of the cooling air, however, then changes depending on the air temperature, therefore increases especially from the second end 7 to the first end 6. If necessary, the mass flow can be controlled depending on the required cooling performance and/or to achieve the desired flow velocity or the desired flow velocity range in the conveyor channel 3.

According to one especially preferred version, in the area of the second end 7, there is a sensor (not shown) for detecting the flow of the supplied or exhausted ambient air. The sensor therefore detects, especially, the volumetric flow or mass flow of the supplied ambient air. This measured value is used as the actual value of the control circuit. As the manipulated variable, the speed and/or the volumetric or mass flow of the branched and redelivered partial flow is varied, especially the rpm of the fan 9 is changed. Preferably, this takes place via a frequency converter. Thus, the injector action of the partial flow can be matched to the changing operating conditions and especially the desired flow of ambient air into the conveyor channel 3 can be achieved. At a constant flow of cooling air which is supplied by the inlet air means 4, a constant ratio of supplied cooling air to ambient air taken in can be achieved in this way. If necessary, this ratio can, however, also be matched to the respective conditions and optionally changed, for example, depending on the desired or necessary cooling performance or other parameters. Thus, control of the flow of supplied cooling air is also possible.

Alternatively or in addition, the exit air means 4 or its exhaust performance can be controlled in order to enable matching to different operating conditions.

Preferably, at least one vibration generator 11 is assigned to the spiral cooler 1 in order to cause the conveyor channel 3, especially the entire spiral conveyor, to vibrate and in this way to achieve conveyance of the workpieces 2 through the conveyor channel 3. In the illustrated example, there are two vibration generators 11 which produce the desired vibrations, for example, via unbalanced shafts.

The conveyor channel 3 is formed in the spiral cooler 1 by bottom elements 12 which are arranged in the manner of a helical line and which are located and held between preferably hollow-cylindrical side walls. One side wall is located radially outside and one side wall is located radially within the bottom elements 12 and the conveyor channel 3. The side walls are made preferably at least essentially without interruptions since no radial inlet lines or exit lines are necessary as in the prior art. However, preferably in the outer side wall, there are closable openings 13 for checks or inspections or the like. As a result of the negative pressure normally prevailing in the conveyor channel 3, if necessary, they can also be opened during operation. Only in the area of the last coil turn or section immediately after delivery of the partial flow by means of the nozzle 10 to the first end 6 of the conveyor channel 3 is there no such opening since an overpressure can prevail there. Preferably therefore, the openings 13 are located only in the areas or sections in which negative pressure also prevails during operation.

Preferably, the spiral cooler 1, between the connection 8 and the nozzle 10 and the first end 6—especially preferably roughly one half coil turn in front of the first end 6 and/or following the nozzle 10 with respect to the flow direction of the cooling air in the conveyor channel 3—has a screening means 14 for separating particles, such as sand, out of the conveyor channel 3. The screening means 14 is formed especially by a perforated bottom element under which a catch bottom 15, as shown in FIG. 2, is located. Captured particles can then be removed or discharged by means of a preferably inside, axially running channel 16 out the conveyor channel 3 to the bottom 17 of the spiral cooler 1 or other receiver. Thus, it is possible to prevent the mold sand on castings or the like from reaching the partial flow to any considerable degree, and thus, being able to adversely affect or even destroy the connection 8, the fan 9 and/or the nozzle 10. These particles can preferably be screened out with very little additional cost based on the vibration drive which is preferably provided for conveying the workpieces 2 by the corresponding vibration of the spiral cooler 1.

The supply of workpieces 2 takes place preferably by means of an especially encapsulated separating trough 19 or the like which is shown schematically in FIG. 1. However, other feed of workpieces 2 can also take place.

The spiral cooler 1 in accordance with the invention has especially an at least essentially cylindrical or hollow cylindrical shape. The spiral cooler 1 can be divided along the plane containing the cylinder axis or coil axis for transport or mounting purposes, as is indicated by the connection 18.

The spiral cooler 1 in accordance with the invention is characterized especially by a simple and thus economical structure. Moreover, the spiral cooler 1 in accordance with the invention is made very durable since, except for the exit and feed of the component flow, no other feeds or exits are necessary along the conveyor channel 3. This reduces or prevents possible damage by workpieces 2 in the conveyor channel 3.

The invention is not limited to cooling. Rather, the supply and discharge of air or other gas can also be used for other purposes, for example, gas treatment or heat treatment. Accordingly, the concept of “spiral cooler” can also be generally understood in the sense of this invention, such that it is especially a coiled or spiral conveyor means, supply and discharge of air or other gas taking place for heat exchange with workpieces and/or for other purposes.

INDUSTRIAL APPLICABILITY

The conveyor and method of the present invention can be used for conveying and cooling a variety of different goods, in particular, hot castings or the like. 

1-21. (canceled)
 22. Spiral cooler for cooling of workpieces with cooling air, comprising: a coiled or spiral conveyor channel for the workpieces, a workpiece entrance for delivery of the workpieces into the conveyor channel being provided in proximity to first end of the conveyor channel, and a workpiece discharge exit being provided in proximity to a second end of the conveyor channel, an inlet air means for feeding the cooling air into the conveyor channel, and exit air means for removing the cooling air from the conveyor channel, wherein the inlet air means is provided in a region of the second end of the conveyor channel and wherein the exit air means is provided in a region of the first end so as to cool workpieces in the conveyor channel in a counterflow manner.
 23. Spiral cooler as claimed in claim 22, wherein the inlet air means has a preferably adjustable nozzle.
 24. Spiral cooler as claimed in claim 22, wherein the inlet air means is made such that the cooling air is delivered from obliquely overhead into the conveyor channel in the area of the second end.
 25. Spiral cooler as claimed in claim 22, wherein the inlet air means is adapted for delivering ambient air together with the cooling air into the second end.
 26. Spiral cooler as claimed in claim 22, further comprising a fan means for withdrawing a partial flow of cooling air from the conveyor channel at an exhaust located in front of the first end and for delivering it again into the conveyor channel at a higher speed for producing a negative pressure in the conveyor channel upstream of the second end.
 27. Spiral cooler as claimed in claim 26, wherein a sensor for detecting the pressure in the conveyor channel or the flow of delivered ambient air is provided in an area of the second end for controlling the fan.
 28. Spiral cooler as claimed in claim 26, wherein the fan means is arranged for delivering the partial flow horizontally or tangentially into the conveyor channel.
 29. Spiral cooler as claimed in claim 26, wherein a screening means is provided in the conveyor channel between the exhaust and the first end.
 30. Spiral cooler as claimed in claim 22, wherein a vibration generator means is provided for conveying the workpieces by vibration of the spiral conveyor from the first end to the second end of the conveyor channel.
 31. Spiral cooler for cooling of workpieces with cooling air, comprising: a coiled or spiral conveyor channel for the workpieces, a workpiece entrance for delivery of the workpieces into the conveyor channel being provided in proximity to first end of the conveyor channel, and a workpiece discharge exit being provided in proximity to a second end of the conveyor channel, an inlet air means for feeding the cooling air into the conveyor channel, exit air means for removing the cooling air from the conveyor channel, and fan means for withdrawing a partial flow of cooling air from the conveyor channel at an exhaust located in front of the first end and for delivering it again into the conveyor channel at a higher speed for producing a negative pressure in the conveyor channel upstream of the second end.
 32. Process for cooling of workpieces in a spiral cooler with a coiled or spiral conveyor channel, comprising the steps of: delivering the workpieces into the conveyor channel at the first end, discharging the workpieces at a second end of the conveyor channel, and delivering cooling air into the conveyor channel in an area of the second end and discharging the cooling air from the conveyor channel in an area of the first end so as to cool the workpieces by a counterflow of the cooling air delivered into the conveyor channel.
 33. Process according to claim 32, comprising the further step of exhausting a partial flow of cooling air from the conveyor channel in front of the first end and delivering it back into the conveyor channel with a higher speed so that a negative pressure is produced in the conveyor channel upstream of the second end.
 34. Process as claimed in claim 32, wherein the inlet air means delivers into the conveyor channel solely on the second end.
 35. Process as claimed in claim 32, the inlet air means delivers into the conveyor channel from obliquely overhead in the area of the second end.
 36. Process as claimed in claim 32, the inlet air means delivers ambient air together with cooling air is into the conveyor channel in the area of the second end by injector action.
 37. Process as claimed in claim 36, wherein the proportion of ambient air in the total flow in the conveyor channel is 10% to 70%.
 38. Process as claimed in claim 32, wherein the proportion of ambient air in the total flow in the conveyor channel is controlled, especially by varying the negative pressure in the conveyor channel.
 39. Process as claimed in claim 32, wherein the partial flow is at least 50% of the total cooling air flow in the conveyor channel.
 40. Process as claimed in claim 33, wherein the higher speed is greater at least by a factor of 2 than the flow velocity of the cooling air in the conveyor channel before exhaust.
 41. Process as claimed in claim 33, wherein the partial flow is used as a control variable in order to control the negative pressure in the conveyor channel.
 42. Process as claimed in claim 32, wherein particles are screened out at least in areas in the conveyor channel and are removed from the conveyor channel.
 43. Process as claimed in claim 32, wherein the workpieces are conveyed from the first to the second end in the conveyor channel. 